Autogenerate known colors and palettes

This will make it a bit easier to make changes

eng/Generator/Commands/ColorGeneratorCommand.cs

@@ -0,0 +1,59 @@
+using System;
+using System.IO;
+using Generator.Models;
+using Scriban;
+using Spectre.Cli;
+using Spectre.IO;
+
+namespace Generator.Commands
+{
+    public sealed class ColorGeneratorCommand : Command<GeneratorCommandSettings>
+    {
+        private readonly IFileSystem _fileSystem;
+
+        public ColorGeneratorCommand()
+        {
+            _fileSystem = new FileSystem();
+        }
+
+        public override int Execute(CommandContext context, GeneratorCommandSettings settings)
+        {
+            var templates = new FilePath[]
+            {
+                "Templates/ColorPalette.Generated.template",
+                "Templates/Color.Generated.template",
+                "Templates/ColorTable.Generated.template"
+            };
+
+            // Read the color model.
+            var model = Color.Parse(File.ReadAllText("Data/colors.json"));
+
+            var output = new DirectoryPath(settings.Output);
+            if (!_fileSystem.Directory.Exists(settings.Output))
+            {
+                _fileSystem.Directory.Create(settings.Output);
+            }
+
+            foreach (var templatePath in templates)
+            {
+                // Parse the Scriban template.
+                var template = Template.Parse(File.ReadAllText(templatePath.FullPath));
+
+                // Render the template with the model.
+                var result = template.Render(new { Colors = model });
+
+                // Write output to file
+                var file = output.CombineWithFilePath(templatePath.GetFilename().ChangeExtension(".cs"));
+                File.WriteAllText(file.FullPath, result);
+            }
+
+            return 0;
+        }
+    }
+
+    public sealed class GeneratorCommandSettings : CommandSettings
+    {
+        [CommandArgument(0, "<OUTPUT>")]
+        public string Output { get; set; }
+    }
+}